This invention relates in general to a lockset, and more particularly to a lockset having an improved actuator mechanism for moving the latch of the lockset in response to rotation of a hand operator.
In U.S. Pat. No. 4,594,864, there is disclosed a lockset having a single latch assembly capable of functioning as a latchbolt and a deadbolt. While the lockset disclosed in the '864 patent has enjoyed considerable commercial success, it has heretofore had one limitation, i.e., the lockset could only be used with a lever type hand operator. A lever type operator can develop a moment arm of a relatively larger magnitude when compared to the moment arm which can be developed by a knob type hand operator, assuming the identical rotational forces are applied to both types of operators. As the internal forces developed by the lockset are resistive of the moment arm generated through the hand operator and are of a somewhat large magnitude in the lockset under consideration, it has been necessary to use lever type operators to ensure that sufficient forces are available to achieve desired movement of the latch assembly.
There are many applications for which a knob type operator may be desired rather than a lever type operator. Since the torsional force developed to move the latch assembly of the lockset when a knob type operator is used is of a smaller magnitude when compared to the torsional force developed through use of a lever type operator, it has been found that the actuator used in the lockset disclosed in U.S. Pat. No. 4,594,864 generally cannot be used with a knob type operator.
In the actuator of the prior art, the force generated therefrom to move the latch assembly is applied radially outward relative to the longitudinal centerline of the lockset. If we consider the centerline to be a fulcrum, the torsional force developed by the hand operator is applied through the actuator to overcome the internal reactive forces of the lockset to move the latch assembly. As is apparent when the actuator force is applied radially outward relative to the fulcrum, the actual force available to overcome the reactive forces is dependent upon the radial distance. The magnitude of the available force is inversely proportional to the radius; that is, as the radial distance increases, the magnitude of the force decreases. To increase the available torsional force to move the latch, it is necessary to reduce the radial distance at which the force is applied by the actuator. By reducing such radial distance, the torsional force developed by the hand operator may be reduced in magnitude since proportionally more of such force will be available to move the latch assembly. It is therefore an object of the invention to provide an improved actuator for a lockset to enable a knob type hand operator to be used on the lockset.